1. Field of the Invention
The present invention relates to a package carrier, and more particularly, to a package carrier for carrying a light emitting semiconductor device and a light receiving semiconductor device.
2. Description of Related Art
Nowadays, electronic devices are being developed to be lighter, thinner, shorter and smaller. Because the electronic devices generally have a small size and light weight, optical detecting devices disposed in the electronic devices are also being designed to be smaller and smaller.
In general, in many commercially available optical detecting devices, a light emitting unit and a receiving unit are packaged separately and are also mounted separately during use. However, in order to reduce cost, size and facilitate assembly thereof, it has become a trend that the light emitting unit and receiving unit are mounted within a single carrier, for example, the light emitting unit and receiving unit are disposed in a two-carrying-area carrier of a plastic material. The carrier is, for example, a leadframe or a printed circuit board (PCB). Because an isolation wall of the plastic material or an inner layer of the bottom PCB cannot completely block optical signals inter-transmission to the light receiving unit, especially when the distance between the light emitting unit and the receiving unit is becoming shorter and shorter, the functional sensitivity and reliability of the optical detecting device can be significantly degraded. For the above reasons, a ceramic carrier has been developed to replace the plastic two-carrying-area carrier to avoid the optical signal transmission between the light emitting unit and the receiving unit through the carrier. However, the ceramic carrier has a high cost thus increasing the fabrication cost of the optical detecting device. In addition, attaching a metal case around each of the light emitting unit and receiving unit has also been proposed to avoid the optical signal of the light emitting unit from being transmitted to the receiving unit. However, this way not only increases the overall size of the optical detecting device, but the fabrication cost of the optical detecting unit is also increased. What is desired, therefore, is to reduce the size as well as the fabrication cost of the optical detecting device.